Generally speaking, a fiber-laying installation comprises a drum on which the core is wound, a plate on which reels of opticaI fiber are mounted, a head for laying the fibers in grooves in the core, at least one distributor die between the reel-carrying plate and the laying head, and then a covering device and a pick-up drum for winding in the core fitted with the fibers. Various traction and control devices are also to be found at various points along the production line.
In such an installation, the laying head is a key member whose main function is to place the fibers in the grooves in the core without subjecting them to high tension or pressure while curving them very little. In addition, the laying head must be as light as possible, particularly when it is the sole rotary component, as occurs when the grooves have an alternating, back-and-forth lay.
Heads for laying optical fibers in alternating lay grooves in a cylindrical core are known and comprise three successive dies: an inlet die: and indexing die: and a die for inserting the optical fibers into the core.
Published European patent application EP-A-0 058 594 relates to a head for simultaneously laying optical fibers in a grooved cylindrical support, where the head comprises a hollow tube having the grooved cylindrical support passing longitudinally therethrough, a washer which is fixed to and axially-aligned with the tube, and which has a central opening therethrough whose inside edge is provided with radially-projecting portions each of which rests on the bottom of a groove in the support, and a part for inserting optical fibers into the support grooves. said part having a central opening aligned with the central opening of the washer and allowing the support to pass therethrough.
However, in such laying heads, the fibers are unguided between the last distributor die and the inlet die to the Iaying head, thereby giving rise to friction between the fibers, or worse still to fiber tangling.
Preferred embodiments of the present invention provide effective guidance for the fibers and keep them apart.